Why is alk so low in my fish only?

[cracker]

I have a 180 fish only. (except one Kenya tree coral) Alk wants to stay at high fives low 6's . I dosed it up to 7.5 now I'm up to 35 mls a day in an effort to keep it there. 7.5. this also an ATo full of saturated Kalk.Just an arbitrary number. I normally wouldn't worry about it seeing how I have only 5 fish so far. However I may be gifted a big Long tentacle nem in the near future. This tank is nutrient deplete so I have to constantly dose No3/Po4 which bounces around from zero to a little.
sal 1.026
No3 2
po4 .o2 to .o5
Dkh as of last night 7.1
No recent Ca or Mg test.
I guess I have to keep dosing but trying to figure out where it's going. Thanks

 

[Randy Holmes-Farley Verified Community Expert]

Is there coralline growing? It can use a lot. In many mixed and soft coral tanks, it may be the biggest consumer.

 

[Halal Hotdog]

^ coraline would be my first guess. Did you start with a significant amount of dry rock?

 

[Fishfinder]

I would test mag before you keep dosing, 35mls a day in a fish only seems high

 

[cracker]

This is a relatively new tank. I have decent coraline on the rock but not growing crazy or anything. Most rock was old LR I had been cooing in darkened barrels for quit a while about 40 lbs of dry base. there is 165lbs of rock in there.

I do a 35 gl w/t every 2 weeks The salt I use test's in the high 9's for alk. I have no hardening of the sand bed. it's too busy blowing around.
Could low mag be the cause?

 

[Larry L]

Why are you dosing nitrate and phosphate in a fish-only tank? Typically people only dose those if they think the levels are too low for their corals to be happy. Usually in fish-only tanks the goal is to keep them low enough to impede algae growth.

 

[Fishfinder]

it could cause the alk to not stay elevated

 

[Randy Holmes-Farley Verified Community Expert]

This is a relatively new tank. I have decent coraline on the rock but not growing crazy or anything. Most rock was old LR I had been cooing in darkened barrels for quit a while about 40 lbs of dry base. there is 165lbs of rock in there.

I do a 35 gl w/t every 2 weeks The salt I use test's in the high 9's for alk. I have no hardening of the sand bed. it's too busy blowing around.
Could low mag be the cause?

Low magnesium can encourage more precipitation of calcium carbonate, as does higher alk and higher pH. But if you are not seeing it on heaters, pumps, sand etc., precipitation may not be a concern.

The 35 mL a day is what product?

 

[cracker]

I'm using (new) 2 prt Ocean's blend & Mrs Waged Pickling lime in the ATO. when I get it ti target I stated dosing the Ca prt in equal amounts. Last time I got iit to 7.5 I started dosing 20 then 25 then 30 now 35 .I'm about to do a Mg test now. Don't really trust this redsea pro kit. Every so often it gives me some crazy number.
I'm dosing the tank in preparation for a nem.

 

[cracker]

Mg tested at 1440 .gotta be pretty close.

 

[Halal Hotdog]

Are you dosing any phosphate binders?

 

[cracker]

just the 2 prt ocean blend , seachemPhos & stump remover . No carbon reactors anything.

 

[Randy Holmes-Farley Verified Community Expert]

I'm using (new) 2 prt Ocean's blend & Mrs Waged Pickling lime in the ATO. when I get it ti target I stated dosing the Ca prt in equal amounts. Last time I got iit to 7.5 I started dosing 20 then 25 then 30 now 35 .I'm about to do a Mg test now. Don't really trust this redsea pro kit. Every so often it gives me some crazy number.
I'm dosing the tank in preparation for a nem.

I am not sure of the potency of the oceans blend you are using so I can't judge if the dose is appropriate or not.:

https://www.oceansblend.com/2_part.html
"Oceans Blend now has a stronger formula for the 2 part Calcium and Alkalinity. "

 

[cracker]

Thank You, I'll just keep up the good fight !